the old value of 500 nodes max has not been true for a very long time rabbitmq and the db still tends to be the bottelneck to scale however beyond 1500 nodes outside of the operational overhead.
We manage our scale with regions as well. With 1k nodes our RabbitMQ isn't breaking a sweat, and no signs that the database would be hitting any limits. Our issues have been limited to scaling Neutron and VM scheduling on Nova mostly due to, NUMA pinning. ________________________________ From: Sean Mooney <smooney@redhat.com> Sent: Tuesday, February 2, 2021 9:50 AM To: openstack-discuss@lists.openstack.org <openstack-discuss@lists.openstack.org> Subject: Re: [ops][largescale-sig] How many compute nodes in a single cluster ? On Tue, 2021-02-02 at 17:37 +0000, Arnaud Morin wrote:
Hey all,
I will start the answers :)
At OVH, our hard limit is around 1500 hypervisors on a region. It also depends a lot on number of instances (and neutron ports). The effects if we try to go above this number: - load on control plane (db/rabbit) is increasing a lot - "burst" load is hard to manage (e.g. restart of all neutron agent or nova computes is putting a high pressure on control plane) - and of course, failure domain is bigger
Note that we dont use cells. We are deploying multiple regions, but this is painful to manage / understand for our clients. We are looking for a solution to unify the regions, but we did not find anything which could fit our needs for now.
i assume you do not see cells v2 as a replacment for multipel regions because they do not provide indepente falut domains and also because they are only a nova feature so it does not solve sclaing issue in other service like neutorn which are streached acrooss all cells. cells are a scaling mechinm but the larger the cloud the harder it is to upgrade and cells does not help with that infact by adding more contoler it hinders upgrades. seperate regoins can all be upgraded indepently and can be fault tolerant if you dont share serviecs between regjions and use fedeeration to avoid sharing keystone. glad to hear you can manage 1500 compute nodes by the way. the old value of 500 nodes max has not been true for a very long time rabbitmq and the db still tends to be the bottelneck to scale however beyond 1500 nodes outside of the operational overhead.
Cheers,